3-Acetyl-1-(2,3-dimethylphenyl)thiourea

In the crystal structure of the title compound, C11H14N2OS, the conformation of the two N—H bonds is anti. The conformation of the C=S and the C=O bonds is also anti. Furthermore, the N—H bond adjacent to the benzene ring is anti to the ortho- and meta-methyl groups. The dihedral angle between the benzene ring and the side chain [N—C(= S)—N—C(=O)—C; maximum deviation = 0.047 (4) Å] is 81.33 (10)°. The NH hydrogen adjacent to the benzene ring and the amide O atom exhibit bifurcated intra- and intermolecular hydrogen bonding. In the crystal, molecules form inversion dimers, which are linked into chains via R 2 2(12) and R 2 2(8) networks.

In the crystal structure of the title compound, C 11 H 14 N 2 OS, the conformation of the two N-H bonds is anti. The conformation of the C S and the C O bonds is also anti. Furthermore, the N-H bond adjacent to the benzene ring is anti to the ortho-and meta-methyl groups. The dihedral angle between the benzene ring and the side chain [N-C( S)-N-C( O)-C; maximum deviation = 0.047 (4) Å ] is 81.33 (10) . The NH hydrogen adjacent to the benzene ring and the amide O atom exhibit bifurcated intra-and intermolecular hydrogen bonding. In the crystal, molecules form inversion dimers, which are linked into chains via R 2 2 (12) and R 2 2 (8) networks.
BTG thanks the University Grants Commission, Government of India, New Delhi, for a special grant under the UGC-BSR one-time grant to faculty.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: NC2285). Thiourea and its derivatives are widely used as precursors or intermediates in synthetic organic chemistry. They are known to exhibit a wide variety of biological activities. As part of our studies on the substituent effects on the structures and other aspects of N-(aryl)-amides (Bhat & Gowda, 2000;Gowda et al., 2006;Shahwar et al., 2012); N-(aryl)-methanesulfonamides (Gowda et al., 2007) and N-chloroarylsulfonamides (Jyothi & Gowda, 2004;Shetty & Gowda, 2004), in the present work, the crystal structure of 3-acetyl-1-(2,3-dimethylphenyl)thiourea has been determined ( Fig. 1).
The conformation of the two N-H bonds are anti to each other, and one of them is anti to the C═S in the urea segment and the other orients away from it. The adjacent N-H bond is anti to the ortho-and meta-methyl groups in the benzene ring. Furthermore, the conformations of the amide C═S and the C═O are anti to each other, similar to the anti conformation observed in 3-acetyl-1-(2-methylphenyl)thiourea (Shahwar et al., 2012).
The hydrogen atom of the NH attached to the phenyl ring and the amide oxygen exhibit a bifurcated hydrogen bonding by showing the simultaneous intra and intermolecular hydrogen bonding. In the crystal, the molecules form inversion type dimers which are linked into infinite chains in terms of R 2 2 (12) and R 2 2 (8) networks through series of N-H···O and N-H···S intermolecular hydrogen bonds, respectively (Table 1, Fig.2).
Experimental 3-Acetyl-1-(2,3-dimethylphenyl)thiourea was synthesized by adding a solution of acetyl chloride (0.10 mol) in acetone (30 ml) dropwise to a suspension of ammonium thiocyanate (0.10 mol) in acetone (30 ml). The reaction mixture was refluxed for 30 min. After cooling to room temperature, a solution of 2,3-dimethylaniline (0.10 mol) in acetone (10 ml) was added and refluxed for 3 h. The reaction mixture was poured into acidified cold water. The precipitated title compound was recrystallized to constant melting point from acetonitrile. The purity of the compound was checked and characterized by its infrared spectrum.
Needle like colourless single crystals used in X-ray diffraction studies were grown in acetonitrile solution by slow evaporation of the solvent at room temperature.

Refinement
All C-H H atoms were positioned with idealized geometry (methyl H atoms allowed to rotate but not to tip) and were refined isotropic with U iso (H) = 1.2 U eq (C) (1.5 for methyl H atoms) using a  (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figure 1
Molecular structure of the title compound, showing the atom labelling scheme and with displacement ellipsoids drawn at the 50% probability level.  Molecular packing of the title compound with hydrogen bonding shown as dashed lines.

Special details
Experimental. Absorption correction: CrysAlis RED (Oxford Diffraction, 2009) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.